1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology

Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)

Mekelle University (Mekelle University) - Ethiopia

1.3 Conditions regarding the use of data documented through WOCAT

When were the data compiled (in the field)?

11/11/2012

The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:

Yes

2.1 Short description of the Technology

Definition of the Technology:

It is a raised wall constructed across a stream/gully using stone, concrete and/or gabion for dual purpose, namely, to pond/store the stream flow behind it for irrigation purpose while at the same time reducing the runoff velocity and enhancing gully rehabilitation.

2.2 Detailed description of the Technology

Description:

A check dam pond is a raised wall constructed across a gully from stone, concrete and/or gabion to store water behind it for irrigation purpose using either gravity or lifting mechanism. The structure generally consists of construction of foundation, apron, retaining wall and the checkdam. The width of the checkdam ranges between 1 - 2 m while the height varies between 1 - 2 m depending up on the gully depth. The length of the checkdam depends on the gully width. The spacing between adjacent checkdams is determined based on two factors, namely, the gradient of the river bed and the availability of potential land that can be irrigated. It is also provided with a number of sluice gates which will be removed during the main rainy season to minimize siltation.

Purpose of the Technology: In addition to storing water for irrigation, check dam ponds decrease slope length, slope angle, runoff velocity and minimize soil erosion.

Establishment / maintenance activities and inputs: Establishment of a check dam pond starts with collection and transportation of stone and sand. The construction is started by setting out the dimensions from the design on the selected site and excavating the foundation for the different parts, namely, key trench, apron and retaining wall. The check dam is then constructed using gabions filled with stones and tightly tied together with wire. Finally the superstructure is plastered using mortar to prevent the passage of water through the body. Gates of about 1 m wide are finally constructed at about 1 m interval and fitted with sluice gates. Maintenance usually involves fixing damaged gates and reinforcing gabions.

Natural / human environment: Check dam pond is implemented in gentle (2 - 5%) and moderate (5 - 8%) slopes and in medium and light soil types of at least 1 m depth. It increases water availability for irrigation and livestock consumption purposes. It also reduces runoff velocity thereby decreasing soil erosion and enhancing gully rehabilitation.

It requires skilled labour and high construction cost. As a result, it is constructed through external support. However, the number of communities seeking for external support and willing to contribute their share is at the rise. The technology minimizes greatly the risk of crop failure and improves the livelihood of the land users.

2.3 Photos of the Technology

2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment

2.6 Date of implementation

If precise year is not known, indicate approximate date:

• less than 10 years ago (recently)

2.7 Introduction of the Technology

Specify how the Technology was introduced:

• through projects/ external interventions

3.2 Current land use type(s) where the Technology is applied

Comments:

Major land use problems (compiler’s opinion): Deforestation and overgrazing, high erosion risk, gully formation and land loss, decline in productivity.

Major land use problems (land users’ perception): Population pressure, deforestation, flood, soil erosion, reduced productivity.

3.3 Further information about land use

Water supply for the land on which the Technology is applied:

• mixed rainfed-irrigated

Number of growing seasons per year:

• 2

Specify:

Longest growing period in days: 150Longest growing period from month to month: June - NovemberSecond longest growing period in days: 105Second longest growing period from month to month: January - April

3.4 SLM group to which the Technology belongs

• water harvesting
• irrigation management (incl. water supply, drainage)
• surface water management (spring, river, lakes, sea)

3.5 Spread of the Technology

Specify the spread of the Technology:

• evenly spread over an area

If the Technology is evenly spread over an area, indicate approximate area covered:

• 1-10 km2

3.6 SLM measures comprising the Technology

Comments:

Main measures: structural measures

3.7 Main types of land degradation addressed by the Technology

Comments:

Main type of degradation addressed: Wg: gully erosion / gullying

Secondary types of degradation addressed: Wt: loss of topsoil / surface erosion, Wm: mass movements / landslides, Wo: offsite degradation effects

Main causes of degradation: deforestation / removal of natural vegetation (incl. forest fires), Heavy / extreme rainfall (intensity/amounts), other natural causes (avalanches, volcanic eruptions, mud flows, highly susceptible natural resources, extreme topography, etc.) specify (Steep topography that increases amount and velocity of flood), population pressure

Secondary causes of degradation: crop management (annual, perennial, tree/shrub), over-exploitation of vegetation for domestic use, overgrazing, floods, land tenure, poverty / wealth, education, access to knowledge and support services

3.8 Prevention, reduction, or restoration of land degradation

Specify the goal of the Technology with regard to land degradation:

• reduce land degradation
• restore/ rehabilitate severely degraded land

Comments:

Main goals: mitigation / reduction of land degradation

Secondary goals: rehabilitation / reclamation of denuded land

4.1 Technical drawing of the Technology

4.2 Technical specifications/ explanations of technical drawing

Check dam ponds are raised walls constructed across a stream/gully using stone, concrete and/or gabion for dual purpose, namely, to pond/store the stream flow behind it for irrigation purpose while at the same time reducing the runoff velocity and enhancing gully rehabilitation.

Location: Tigray. Kilte Awlaelo

Date: 10/10/2014

Technical knowledge required for field staff / advisors: high

Technical knowledge required for land users: high

Technical knowledge required for Engineer/designer: high

Main technical functions: control of dispersed runoff: impede / retard, reduction of slope length

Secondary technical functions: reduction of slope angle, increase of infiltration, increase of groundwater level / recharge of groundwater, sediment retention / trapping, sediment harvesting

Wall/ barrier
Vertical interval between structures (m): n/a
Spacing between structures (m): n/a
Height of bunds/banks/others (m): 1 - 2
Width of bunds/banks/others (m): 1 - 2

Construction material (stone): Stones are usually shaped in order to piece together very well.

Construction material (concrete): The chekdam is usually plastered by concrete on the upstream side to prevent the passage of water th

Construction material (other): Gabion, Sheet metal and Angle iron.

Slope (which determines the spacing indicated above): 2 - 8%

Lateral gradient along the structure: 0%

4.3 General information regarding the calculation of inputs and costs

other/ national currency (specify):

Birr

Indicate exchange rate from USD to local currency (if relevant): 1 USD =:

18.0

4.4 Establishment activities

	Activity	Type of measure	Timing
1.	Site clearance and excavation of foundation	Structural	Dry season
2.	Stone collection and transportation	Structural	Dry season
3.	Sand collection and transportation	Structural	Dry season
4.	Gabion masonry work	Structural	Dry season
5.	Plastering	Structural	Dry season

4.5 Costs and inputs needed for establishment

	Specify input	Unit	Quantity	Costs per Unit	Total costs per input	% of costs borne by land users
Labour	Labour	ha	1.0	4678.0	4678.0	25.0
Construction material	Cement	ha	1.0	953.0	953.0
Construction material	Gabion	ha	1.0	6268.0	6268.0
Construction material	Sheet metal	ha	1.0	44.0	44.0
Construction material	Angle iron	ha	1.0	56.0	56.0
Total costs for establishment of the Technology					11999.0

Comments:

Duration of establishment phase: 6 month(s)

4.6 Maintenance/ recurrent activities

	Activity	Type of measure	Timing/ frequency
1.	Fixing damaged gates and reinforcing gabions	Structural	Dry season

4.7 Costs and inputs needed for maintenance/ recurrent activities (per year)

Comments:

Machinery/ tools: Digging hoe, shovel, hammer, crow bar

Since the check dam ponds generally vary in depth, width and most importantly in length depending up on the gully profile, calculation of cost per meter length will not be a reliable presentation. As a result, one typical check dam pond was selected and the total volume of the structure and the corresponding total cost of construction calculated. Then, the cost per cubic meter of the check dam was determined by dividing the total construction cost to the total volume of the structure.

The calculation includes the cost for the purchase of industrial materials (cement, gabion, sheet metal and angle iron) and cost of labour used for the construction including site clearance and excavation of foundation, stone and sand collection and transportation, gabion masonry work and plastering.

The price of the industrial materials and the labour wage used in the cost calculation apply to 2012. The daily labour wage for plastering is 180 Birr while it is 50 Birr for all other works.

4.8 Most important factors affecting the costs

Describe the most determinate factors affecting the costs:

Labour, availability of construction material, depth and width of gully.

5.1 Climate

5.2 Topography

5.3 Soils

If available, attach full soil description or specify the available information, e.g. soil type, soil PH/ acidity, Cation Exchange Capacity, nitrogen, salinity etc.

Soil fertility is low (medium soils, ranked 1) and very low (light soils, ranked 2)
Soil drainage/infiltration is medium (ranked 1) and good (ranked 2)
Soil water storage capacity is medium (ranked 1) and low (ranked 2)

5.4 Water availability and quality

Comments and further specifications on water quality and quantity:

Availability of surface water is good (September - January). Also medium (February-June)

5.5 Biodiversity

5.6 Characteristics of land users applying the Technology

Indicate other relevant characteristics of the land users:

Land users applying the Technology are mainly common / average land users
Population density: 100-200 persons/km2
Annual population growth: 2% - 3%
10% of the land users are rich and own 10% of the land.
60% of the land users are average wealthy and own 55% of the land (35 Birr/day/person).
30% of the land users are poor and own 35% of the land.

5.7 Average area of land owned or leased by land users applying the Technology

5.8 Land ownership, land use rights, and water use rights

Land ownership:

• state

Land use rights:

• communal (organized)
• individual

Water use rights:

• communal (organized)

5.9 Access to services and infrastructure

6.1 On-site impacts the Technology has shown

Socio-economic impacts

Production

Water availability and quality

Income and costs

Socio-cultural impacts

Ecological impacts

Water cycle/ runoff

Soil

Biodiversity: vegetation, animals

6.2 Off-site impacts the Technology has shown

6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)

Climate-related extremes (disasters)

Hydrological disasters

	How does the Technology cope with it?
general (river) flood	not well

6.4 Cost-benefit analysis

How do the benefits compare with the establishment costs (from land users’ perspective)?

How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?

6.5 Adoption of the Technology

Comments:

100% of land user families have adopted the Technology with external material support

500 land user families have adopted the Technology with external material support

There is no trend towards spontaneous adoption of the Technology

Comments on adoption trend: There is no trend for spontaneous adoption due to high costs. However, communities are increasingly seeking external support to implement this technology.

6.7 Strengths/ advantages/ opportunities of the Technology

Strengths/ advantages/ opportunities in the land user’s view
Increased water availability for irrigation and livestock consumption How can they be sustained / enhanced? Watershed management
Reduced soil erosion How can they be sustained / enhanced? Construction of retaining walls
Increased employment opportunity and income from irrigation How can they be sustained / enhanced? Cultivation of high value crops

Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view
Increased water availability for irrigation as well as livestock consumption How can they be sustained / enhanced? Integrated watershed management
Reduce slope length, angle and erosion risk and enhance gully rehabilitation How can they be sustained / enhanced? Regular maintenance of the structure

6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them

Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view	How can they be overcome?
High cost of construction	Selecting a site that has good availability of construction material and that can irrigate as large area as possible.
Require skilled labour	Training of land users
Labour intensive	Mass mobilization

7.2 References to available publications

Title, author, year, ISBN:

Staff members of the Kilte Awlaelo Wereda Office of Agriculture and Rural Development and Office of Water Resources Development